1. Field
The exemplary embodiments relate to an image sensor including a color separation element and an image pickup apparatus including the image sensor, and more particularly, to an image sensor having an improved light use efficiency by using a color separation element, and an image pickup apparatus including the image sensor.
2. Description of the Related Art
Color display devices or color image sensors usually display an image of various colors or detect a color of incident light by using a color filter. An RGB color filter method, in which, for example, a green filter is arranged at two pixels of four pixels and a blue filter and a red filter are arranged in the other two pixels, is most widely employed by a currently used color display device or color image sensor. In addition to the RGB color filter method, a CYGM color filter method may be employed in which color filters of cyan, yellow, green, and magenta, which are complementary colors, are respectively arranged at four pixels.
However, a color filter may have a low light use efficiency because the color filter absorbs light of colors other than a color corresponding to the color filter. For example, when an RGB color filter is in use, only ⅓ of the incident light is transmitted and the other portion, that is, ⅔, of the incident light is absorbed. Accordingly, the light use efficiency may be about 33%. Accordingly, for the color display device or a color image sensor, most of a light loss is generated in the color filter.
Recently, to improve the light use efficiency of the color display device or color image sensor, a color separation element is being used instead of the color filter. The color separation element may separate the color of an incident light by using the diffraction or refraction characteristics of light that vary according to a wavelength of the light. The colors separated by the color separation element may be provided to pixels corresponding to the colors, respectively.